Conventionally, amplifier circuits have typically been realized by using operational amplifiers. In recent years, a discrete-time type amplifier circuit has been proposed, which adopts a charge pump circuit and a comparator in place of the operational amplifier. The power consumption of the discrete-time type amplifier circuit is lower than the power consumption of the amplifier circuit using the operational amplifier.
However, in a certain conventional discrete-time type amplifier circuit, a time difference (also called “mismatch”) occurs, in some cases, between a voltage of an input and a voltage of an output at a time of the start of an amplification operation. It is thus difficult to improve the precision (resolution) of this amplifier circuit. On the other hand, in another conventional discrete-time type amplifier circuit, a switch is inserted between the input and output, and therefore the mismatch may possibly be improved. However, conversely, degradation in isolation occurs between the input and output, and also nonlinear distortion of this switch occurs. Thus, it is also difficult to improve the precision of this amplifier circuit.